Politicians probably made a quick photo op at the site, shook some hands, and generally left the site. The workers were in all the rubble for weeks and months, cleanup took quite a long while. It's very different being exposed to dangerous materials for a small amount of time vs months of working on the area. Cancer rates are generally some sort of chance that continues to increase the longer one is exposed to the harmful chemicals. Sometime who smokes for 30 years is much more likely to have lunch cancer than the person who smokes random weekends when they're drunk.